Sex- and age-dependent patterns of survival and breeding success in a long-lived endangered avian scavenger

Abstract

In long-lived species, the age-, stage- and/or sex-dependent patterns of survival and reproduction determine the evolution of life history strategies, the shape of the reproductive value, and ultimately population dynamics. We evaluate the combined effects of age and sex in recruitment, breeder survival and breeding success of the globally endangered Egyptian vulture (Neophron percnopterus), using 31-years of exhaustive data on marked individuals in Spain. Mean age of first reproduction was 7-yrs for both sexes, but females showed an earlier median and a larger variance than males. We found an age-related improvement in breeding success at the population level responding to the selective appearance and disappearance of phenotypes of different quality but unrelated to within-individual aging effects. Old males (≥8 yrs) showed a higher survival than both young males (≤7 yrs) and females, these later in turn not showing aging effects. Evolutionary trade-offs between age of recruitment and fitness (probably related to costs of territory acquisition and defense) as well as human-related mortality may explain these findings. Sex- and age-related differences in foraging strategies and susceptibility to toxics could be behind the relatively low survival of females and young males, adding a new concern for the conservation of this endangered species.

Evaluating European LIFE conservation projects: Improvements in survival of an endangered vulture

“…After LIFE actions, all age classes showed high survival prospects: 95% for juveniles and subadults and 93% for adults. This adult survival estimate is similar to other stable Egyptian vulture populations in France (Lieury et al., ) and the Balearic Islands (Sanz‐Aguilar, De Pablo, et al., ) and higher than those estimated for threatened Spanish populations in the Ebro Valley and Andalusia (Sanz‐Aguilar et al., ; Sanz‐Aguilar, Sánchez‐Zapata, et al., ) and for the Balkan populations (Oppel et al., ). Population viability in long‐lived species is highly dependent on adult survival (Saether & Bakke, ).…”

“…Survival of adult, and to a lesser extent, subadult individuals, is the key parameter influencing population viability and dynamics of long‐lived species with deferred sexual maturity (Saether & Bakke, ; Sergio et al., ). However, long‐term monitoring programmes are required to obtain robust survival estimates (Sanz‐Aguilar et al., ). Long‐lived species show age‐structured patterns of survival, which generally increases with age as a result of age‐related improvements in several skills (e.g.…”

Effects of early-life competition and maternal nutrition on telomere lengths in wild meerkats

“…Our finding that variation in offspring telomere lengths is associated with maternal and paternal age should be interpreted with caution. Pups born to older mothers had longer telomeres, and while a female could provide better care for offspring as she grows older, it is equally possible that early mortality of poor-quality females leads to disproportionate numbers of high-quality females in older cohorts [61,62]. The positive effect of maternal age on pup telomere lengths may therefore be due to selective disappearance, rather than within-female change.…”

Supplementary feeding as a source of multiresistantSalmonellain endangered Egyptian vultures

“…This area holds numerically important and increasing populations of Griffon vultures that are highly dependent on livestock carrion at SFSs (Blanco, ). Contrary to this large vulture species, the Egyptian vulture has suffered a strong decline in the last few decades in the study area (Segovia province), passing from 43 pairs in 1993 to about 25 pairs in the last years (Del Moral & Martí, ; Sanz‐Aguilar et al., ; author unpubl. data).…”